The soliton states localized at a point defects are investigated by us
ing the nonlinear Schrodinger equation for various signs of the nonlin
earity and for different types of defects. The quantum interpretation
of these nonlinear localized modes is given in terms of bound states o
f a large number of Bose particles. The dynamic properties and stabili
ty of these states for different types of interaction between elementa
ry excitations with one another and with the defect are investigated.
The boundaries of the region of existence and stability of ''impurity'
' solitons are determined depending on the ''intensity'' of the defect
, and the frequency of small oscillations of a soliton near the defect
is calculated. (C) 1997 American Institute of Physics.